Draft gear



A. C. DAVIDSON DRAFT GEAR 4 Sheets-Sheet 1 Filed Dec. 12', 1 921 /NVEN7'0R.

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Dec. 1 1,520,536

A. c. DAVIDSON DRAFT GEAR Filed Dec. 12, 1921 4 Sheets-Sheet 2 Haas 3 He. 4

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A. c. DAVIDSON DRAFT GEAR Filed D80. 12, 1921 4 S heecS -Sheet a if, m Arr'rs.

Patented Dec. 23, 1924.

UNITED STATES ARTHUR C. DAVIDSON, OF CHICAGO, ILLINOIS.

DRAFT GEAR.

Application filed December 12, 1921.

To all whom it may concern-z Be it known that I, ARTHUR C. DAVIDSON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Draft Gears, of which the following is a specification.

This invention pertains particularly to draft gears of the type utilizing both spring-pressure and friction in bufiing and pulling operations.

The primary object of the invention is to provide an improved and simplified construction which is strong and durable, which can be manufactured at very moderate cost, and which is particularly well adapted for use in connection with cars where the ordinary duty of the draft-gear is not excessive, the improved draft-gear being adapted, however, to withstand extraordinary shocks when called upon to do so. A further object is to provide a simplified construction involving few parts which can be assembled with the greatest facility.

The invention as illustrated, in its preferred embodiment, in the accompanying drawing, in which- Fig. 1 represents a broken plan View, partly in section, of the improved draftgear and the sub-structure of a car on which it is mounted; Fig. 2, a vertical sectional view of the same; Figs. 3, at and 5, broken transverse vertical sections taken as indicated at the correspounding lines on Fig. 2; Fig. 6, an inner perspective view of one of the friction shoes employed; Fig. 7, a broken plan view, partly in section, showing a modification; Fig. 8, a vertical sectional view of the construction shown in Fig. 7 Figs. 9, l0 and 11, broken vertical sectional views taken as indicated at the corresponding lines on Fig. 8; and Fig. 12, a vertical sectional view showing a modification of the internal expander employed.

Referring to Figs. 1 to 6, inclusive, A, A represent longitudinal frame members constituting a part of a sub-structure of a carbody; A a transverse plate connecting said members at their lower portions; A a plate forming a covering above the space between the members A, A A a pair of front stops for the draft-gear, said stops being secured to the inner sides of the longitudinal members, A, A 1- a pair of rear stops for the draft-gear similarly secured Serial No. 521,698.

to the members A, A B, a front follower plate or stop which engages the front set of stops mentioned; C, the improved draftgear interposed between the stops; D, a longitudinal yoke embracing the draftgear; and D a draw-bar equipped near its rear end with a transverse pin D which extends freely thru a slot 1 in the furcated front end of the yoke and works freely in guide-slots 2 with which the frame-members A, A are provided.

The construction providing for the mounting of the draft-gear and the connection thereof with the draw-bar may be any desired construction. In the form shown, the yoke D is provided at its front end with furcations 1 thru which the transverse slot 1 extends. The yoke D has an upper longitudinal member l a lower longitudinal member 1, a front wall or shoulder 1 and a rear wall or shoulder 1 The draftgear C comprises an outer member or casing C which has one end portion provided with an internal taper surface 3; an annular series of segmental shoes C having friction contact with the internal taper surface 3, the corresponding end of the casing C being open and the shoes C being extended as to project beyond the open end; a central expander C which is provided on all of its sides with series of wedge surfaces which engage corresponding wedge surfaces with which the friction shoes are provided at their inner surfaces; a heavy service spring (3* confined between the end wall of the casing C and the inner ends of the friction shoes; and a smaller restoration spring C confined between the end wall of the casing C and an abutment with which the central expander G is provided.

In the form shown in Figs. 1 to 5, inclusive, the casing C is of cylindrical form. It is open at one end and is provided at the other end wit-h an end wall 4. which serves as an abutment or hearing for the adjacent ends of the coil springs. The casing is shown provided at its closed end with integral lateral lugs 5 which serve as stops adapted to bear against the rear set of stops A The casing is further provided at its open end with lateral lugs 6 which are formed integrally with the casing. Also, the casing is provided at its opposite sides vith horizontal ribs or flanges 7 which are formed integrally with the casing, the ends tit) III

of the ribs 7 being formed integrally with the lugs 5 and 6. The function of the longitudinal ribs 7 is to strengthen the casing and adapt it to transmit a solid blow in case the draft-gear should, under exceedingly heavy impact, collapse sufficiently to enable the follower B to strike the front end of the casing.

The inner taper surface 3 of the casing C is of largest diameter at the front end of the casing and the diameter contracts in a direction away from the open end of the casing, so that the annular surface 3 is, in fact, a frustoconical surface of very slight taper. It will be noted that the open end portion of the casing is provided with a thickened wall, this portion of the casing being that which is subjected to bursting strain when the draft-gear is collapsed.

Each of the segmental shoes C is preferably of the form shown in Fig. 6. Preferably six of these friction shoes are our ployed. Each shoe is of elongated form and of curved cross-section, and each shoe is provided on its inner surface with a longitudinally spaced series of wedge surfaces 8. These wedge surfaces coact with longitudinal series of wedge surfaces 9 with which the central expander C is provided, that is, the expander is provided with wedge surfaces on all of its sides which are adapted to coact with the wedge sur faces of the six segmental shoes. Each of the wedge surfaces 9 may form a part of an annular or conical wedge surface.

The central expander C is preferably made hollow or of tubular form and provided with a transverse wall 10 which serves as an abutment or bearing for the front end of the small diameter spring C l/Vhen the parts of the draft-gear are assembled the springs are placed under considerable compression and are held thus by a bolt 11 which connects the central portion of the ,end wall 4 of the casing with the internal transverse wall 10 of the expander. The bolt extends freely thru perforations in these walls, so that the collapsing action of the draft-gear is not interfered with. In the illustration given, an annular plate 12 is interposed between the ends of the fric tion shoes C and the adjacent end of the heavy spring C The inner spring extends thru the annular plate 12.

In the modification shown in Figs. 7 to 12. inclusive, the construction is the same as already described except that the frame of the casing is changed and the spring arrangement is changed somewhat. In

these figures, those parts which correspond precisely with the parts already described are correspondingly lettered. The casing, which is of modified form, is designated G. This casing has one endprovided with a barrel portion 13 which has an internal taper surface 13 which corresponds with the taper surface 3 in the first described construction. The other end of the casing is enlarged in a transverse direction and left open at its sides, thus providing atop wall 14 and a bottom wall 14?. The enlarged portion of the casing fits freely be tween the frame members A and A of the sub-structure of the car. The plates 14: and 14* which form the top and bottom walls of one portion of the casing are connected by an integrally formed end walll i Two sets of springs C and C are interposed between the wall 14? and a transverse plate 15 which bears against the inner ends of the friction shoes C Each set comprises a heavy outer spring 16 and a spring 16* of smaller diameter, located within the spring. A restoration spring C is located in the expander C being interposed between the plate 15 and the transverse wall 10. The springs are held under the desired compression bya longitudinal bolt 17 which connects, the end wall 1 1 of the casing with the transverse wall 10, of the expander. This bolt is free to move thru the wall 10 and thru a central perforation with which the plate 15 is provided. The operation of the modified form is the same as that of the first described construction. However, a large increase in spring resistance is obtained by the arrangement of the springs in the modified form.

Fig. 12 shows a modified form of the central expander. The expander is here designated C It corresponds with the expander previously described, except that it is provided with a head or flange B which is integrally formed, the head serving as a substitute for the follower B. In this case, the inner transverse wall 10 of the expander is moved further towards the outer end of the expander, thus allowing room for alonger restoration coil. Obviously, the form of expander shown in Fig. 12 may be employed in either of the constructions described above.

Referring to the construction shown in Figs. 1 and 2, in the butting operation the follower B is forced rearwardly away from the stops A. The wedge surfaces 9 of the central expander serve to expand the friction shoes, causing them to exert .a heavy friction action against the conical interior-surface 3 of the casing. The bulfing action is also resisted by the heavy service spring (3* as well as the restoration spring C. When a pull is exerted on the drawbar, the follower B remains in contact with the front stops A while the casing C is forced forwardly over thefriction shoes. The collapsing action is the same, obvious ly, in both operations. The restoration spring serves. to effect release of the ex- Inn pander with respect to the friction shoes and thus to effect release of the friction shoes with relation to the friction surface of the casing.

The disposition of the friction shoes with relation to the central expander and the disposition of the plurality of Wedge surfaces is such as to cause substantially uniform radial pressure to be exerted on the interior of the friction Wall of the casing at every point of contact. The result is that a very high frictional resistance is obtained in the operation of the gear and this is supplemented by a very high resistance on the part of the compression springs.

The improved construction utilizes in a very high degree the available space Which is available in cars of standard construction for the reception of the draft-gear the parts of the draft-gear may be assembled and held in assembled condition by means of the central bolt; and the draft-gear may then be introduced with facility into the position which it occupies in the car structure. In the modified construction, as appears from Fig. 10, the springs C and C can be inserted thru the open sides of the rectangular portion of the casing after the insertion of the plate 15.

The foregoing detailed description has been given for clearness of understanding only, and n0 unnecessary limitations should be understoor'l therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

What I regard as new, and desire to secure by Letters Patent, is

1. In a draft-gear, the combination of a casing provided at one end With a spring bearing and having an open-ended tubular portion at its other end provided With an inner friction surface, an annular series of shoes Within said tubular portion, each shoe having its inner surface provided With a series of longitudinally spaced wedge surfaces, a central hollow expander provided on all sides with a series of longitudinally spaced Wedge surfaces coacting With said first-named wedge surfaces, a coil spring device confined between the inner ends of said friction shoes and said spring bearing, and a restoration spring extending into said hollow expander and tending to retract said expander.

2. In a draft-gear, the combination of a casing l'iaving a barrel portion at one end and having a transversely enlarged portion at the other end, said barrel portion being provided with an internal friction surface, an annular series of shoes contacting With said friction surface, each of said shoes being provided with a longitudinally spaced series of wedge surfaces, at central wedgemember encircled by said shoes and provided on all sides with a series of wedge surfaces coacting with said first-named wedge surfaces, a transverse follower-plate bearing against the inner ends of said friction shoes, heavy coil springs disposed on opposite sides of the longitudinal center of said. casing and confined between the end wall of the casing and said follower-plate, and a restoration spring housed in said central expander and having one end bearing against said follower-plate and the other end bearing against an abutn'ient with Which said expander is provided.

ARTHUR C. DAVIDSON. 

